Plate heat exchanger

ABSTRACT

The present invention concerns a plate heat exchanger for at least two heat exchanging fluids. The heat exchanger is permanently joined and includes at least one core of plates with corrugated heat exchanging plates ( 1-4 ) creating plate interspaces between one another, at least two end plates ( 5 ) as well as inlet devices ( 6 ) and outlet devices ( 6 ) for the heat exchanging fluids. At least one of the end plates ( 5 ) is equipped with at least one port hole communicating with an inlet channel or an outlet channel. At least one of the mentioned inlet devices ( 6 ) and outlet devices ( 6 ) has both a connection part ( 7 ) equipped with a channel and a transition part ( 8 ) with an envelope surface and equipped with a channel. An intersectional line between an imaginary elongation of the mentioned envelope surface in the direction of the generatrix for the envelope surface in every point of contact between the envelope surface and the end plate ( 5 ) on the one hand and a plane having contact areas within the plate interspaces between the two heat exchanging plates ( 1,2 ) that are closest to the transition part ( 8 ) in the core of plates on the other hand circumscribes a plurality of connecting points ( 10 ) between the mentioned two heat exchanging plates ( 1, 2 ).

FIELD OF THE INVENTION

The present invention concerns a plate heat exchanger for at least twoheat exchanging fluids which heat exchanger is permanently joined andcomprises at least one core of plates with corrugated heat exchangingplates creating plate interspaces between each other, at least two endplates as well as inlet devices and outlet devices for the heatexchanging fluids.

BACKGROUND OF THE INVENTION

Permanently joined plate heat exchangers are used to an increasingextent. The joining together may be done by brazing but also welding andgluing are used. At a pressure overloading a permanently joined plateheat exchanger leakage will arise and the leakage is generally locatedto the port areas and/or the circumferential areas of the heatexchanging plates in connection to the inlet and outlet channels. Theplate heat exchanger has within the port areas of the plates relativelylarge projected areas without connecting joints between the heatexchanging plates. Upon these areas forces from pipe loads and fluidpressure are acting. The joints which are situated closest to the portareas of the plates run the risk of being over-loaded and torn up.

U.S. Pat. No. 5,462,113 shows a plate heat exchanger for three fluids.The heat exchanger comprises a core of plates with heat exchangingplates, end plates and inlet devices and outlet devices for the heatexchanging fluids. The attachment of the end plate 12 to the extrasealing plate 16 is wide in comparison with the port channel for theheat exchanging fluid R1 and will probably contribute to an increasedresistance to pressure load. The resistance may still be improved.

SUMMARY OF THE INVENTION

The purpose of the invention is to create a stronger permanently joinedplate heat exchanger for at least two heat exchanging fluids. Theinvention thus comprises a plate heat exchanger for at least two heatexchanging fluids which heat exchanger is permanently joined andcontains at least one core of plates with corrugated heat exchangingplates creating plate interspaces between each other, at least two endplates as well as inlet devices and outlet devices for the heatexchanging fluids. Each one of the heat exchanging plates is equippedwith at least four port holes creating an inlet channel and an outletchannel through the core of plates for each one of the fluids. At leastone of the end plates is equipped with at least one port hole incommunication with an inlet channel or an outlet channel. The inletchannels and the outlet channels for a first and a second fluid,respectively, are in fluid communication with a first and a second setof plate interspaces, respectively.

At least one of the mentioned inlet devices and outlet devices comprisesboth a connection part equipped with a channel and a transition partwith an envelope surface and equipped with a channel, the channel in thetransition part fluid tightly connecting the channel in the connectionpart with one of the port holes in one of the end plates. Anintersectional line between an imaginary elongation of the mentionedenvelope surface in the direction of the generatrix for the envelopesurface in every point of contact between the envelope surface and theend plate 5 on one hand and a plane comprising contact areas in theplate interspaces between the two heat exchanging plates that areclosest to the transition part in the core of plates on the other handcircumscribes a plurality of connecting points between the mentionedheat exchanging plates.

The present form of execution of a heat exchanger shows due to the wideattachment to the end plate of the transition part in comparison withthe port channel a larger pressure durability than before in thisexposed area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in perspective view and in principle a permanently joinedplate heat exchanger according to the invention for two heat exchangingfluids.

FIG. 2 shows in a perspective view a part of a permanently joined plateheat exchanger according to the invention whereby only one inlet oroutlet device and the closest to this device situated part of the heatexchanger are shown.

FIGS. 3a and 3 b show in a cross-section the inlet or outlet device, theend plate and four of the heat exchanging plates in the core of platesaccording to FIG. 2.

FIGS. 3c and 3 d show in cross-section the inlet or outlet device, theend plate and four of the heat exchanging plates in the core of platesaccording to two alternative embodiments.

DETAILED DESCRIPTION

The plate heat exchanger according to the invention in FIG. 1 is shownin principle and comprises a core of plates with heat exchanging plates1, end plates 5 and inlet devices 6 and outlet devices 6 for two heatexchanging fluids.

FIG. 2 shows a part of the plate heat exchanger according to theinvention. The figure shows a core of plates with heat exchanging plates1, end plates 5 as well as an inlet device or an outlet device for aheat exchanging fluid, the inlet or outlet device comprising aconnection part 7 and a transition part 8.

How the construction appears in cross-section is evident from FIGS. 3aand 3 b where for the sake of simplicity only three heat exchangingplates 1-3 have been included. The core of plates may of course beexecuted in the wished thickness with the wished amount of heatexchanging plates due to the effect need, the space which is availablefor the installation etc. The construction according to FIGS. 3a and 3 bhowever differs from the one according to FIG. 2 in such a way that thetransition part 8 in FIG. 3 has been executed in one piece with the endplate 5 while the transition part 8 in FIG. 2 afterwards has been addedto the end plate 5.

The connection part 7 is equipped with an inner channel and aimed atbeing connected to a pipe system in a plant of some kind. The transitionpart 8, also this one equipped with an inner channel, fluid tightlyconnects the channel within the connection part 7 with a port hole in anend plate 5. The transition part 8 may be executed in one piece with theconnection part 7 and/or, as mentioned above, with the end plate 5.

An intersectional line between an imaginary elongation of the envelopesurface of the transition part 8 in the direction of the generatrix ofthe envelope surface in every point of contact between the envelopesurface and the end plate 5 on one hand and a plane comprising contactareas within the plate interspace between the two heat exchanging plates1, 2 situated closest to the transition part 8 in the core of plates onthe other hand (see FIG. 3a) circumscribes a plurality of connectingpoints 10 between the mentioned two heat exchanging plates 1, 2. As afurther accentuation of the determinations an intersectional linebetween an imaginary elongation perpendicular to the plates 1-5 of theenvelope surface for the transition part 8 on one hand and the mentionedplane comprising contact areas in the plate interspace between the twoheat exchanging plates 1, 2 closest to the transition part in the coreof plates on the other hand (see FIG. 3b) may circumscribe a pluralityof connecting points 10 between the mentioned heat exchanging plates 1,2. In connection to the elongation of the envelope surface one takes asa starting point a contact line between the mentioned envelope surfaceand the end plate 5.

The mentioned intersectional line may, depending on the plate size,circumscribe 2-200, preferably 3-100 and most preferred 5-50 connectingpoints 10. The circumscribed connecting points 10 are peripherallysituated around the inlet or outlet channel and are present mainlyevenly distributed over the present plate areas within an undividedcircular sector with a central angle of at least 90 degrees, preferablymore than 225 degrees and most preferred 360 degrees where the centre ofthe circle coincides with the centre of the inlet or outlet channel. Thementioned connecting points 10 may be brazing joints but also weldingand gluing may, as mentioned earlier, be used as a method connection.

All the inlet devices 6 and outlet devices 6 may be attached to the sameend plate 5. If this is not the case the inlet device 6 for a firstfluid and the outlet device 6 for a second fluid for example may insteadbe attached to a first end plate 5 and the inlet device 6 for thementioned second fluid and the outlet device 6 for the mentioned firstfluid may be attached to a second end plate 5.

Each one of the present end plates 5 may possess an area which issmaller than half the area for one of the heat exchanging plates 1-4 inthe core of plates whereby the area without regard to the areaenlargement due to corrugations is meant. Two or more end plates of thekind described may be mounted in the same end of the core of plates butin different ends and/or corners of the closest situated heat exchangingplate. The end plates 5 may fluid tightly connect to the core of platesand in the outer boarders of the core show edge areas 9 at an angle tothe main plane of extension for the plates for contacting and attachmentto similar edge areas upon the closest situated heat exchanging plate1-4 in the core of plates.

The connection part 7 may be cylindrical and have a larger wallthickness than the associated transition part 8. The transition part 8may be executed in the form of a channel equipped and thus hollowtruncated cone (see FIGS. 3a, 3 b and 3 c)or in the form of a channelequipped and thus hollow cylinder(see FIG. 3d). The transition part 8however does not need to be rotation symmetrical. The transition part 8,the end plate 5 and as a consequence the flange-like edge area 9 are,especially in a corner of the plate heat exchanger, with advantage ofmainly the same thickness.

The dimensions for pipes and pieces of joint are standardized. Thepresence of the transition part 8 makes the preservation of the up tonow mainly used dimensions and positions for the connection parts 7possible at the same time as the contact area for the attachment ofinlet devices 6 and/or outlet devices 6 to the end plate 5 is movedradially outwards, i.e. “past” a number of in relation to the portchannels peripherally situated connecting points 10. The strains uponthese exposed connecting points 10 between plates hereby diminish andthe so called tearing forces are neutralized. The thickness of the goodsin the end plate 5 may be diminished in comparison with prior art forthe same demand concerning the pressure load as before. Hereby also thesusceptibility of the construction to thermal cycles and fatigue willdiminish.

By the dividing up of the inlet device 6 and the outlet device 6 into aconnection part 7 and a transition part 8 also the advantage is achievedthat the connection parts 7 may be mounted afterwards after the plateheat exchanger with the transition part 8 have been mounted and havepassed the brazing furnace. Hereby space within the furnace is savedsince this may be filled more effectively with more cores of heatexchangers at a time, induction brazing may be used and the materialwithin the connecting parts 7 may afterwards be chosen freely.

If instead connection part/parts 7, transition part/parts 8 and the endplate 5 are arranged in one piece by pressing of a plane plateespecially low manufacturing costs are achieved.

The invention is not restricted to the forms of execution shown here butmay be varied in accordance with the following patent claims.

What is claimed is:
 1. A plate heat exchanger for at least two heatexchanging fluids, said heat exchanger being permanently joined andcomprising at least one core of corrugated heat exchanging plates (1-4),said plates forming at least first and second sets of plate interspacesbetween one another, at least two end plates (5) and inlet devices (6)and outlet devices (6) for the at least two heat exchanging fluids, eachone of the heat exchanging plates (1-4) having at least four port holes,thus forming an inlet channel and an outlet channel through the core ofplates for each of the at least two heat exchanging fluids, at least oneof the end plates (5) being equipped with at least one of the portholes, each said at least one of the port holes communicating with oneof the inlet channels or one of the outlet channels and the inletchannels and the outlet channels for a first and a second of said atleast two heat exchanging fluids, respectively, being in fluidcommunication with the first and the second sets, respectively, of plateinterspaces wherein at least one of the inlet devices (6) and outletdevices (6) comprises both a connection part (7) equipped with a channeland a transition part (8) with an envelope surface and equipped with achannel, the channel in the transition part (8) fluid tightly connectingthe channel in the connection part (7) with the at least one of the portholes in one of the end plates (5), the transition part (8) being madein one piece with the end plates (5), an intersectional line between animaginary elongation of the envelope surface, in the direction of ageneratrix for the envelope surface in every point of contact betweenthe envelope surface and the end plate (5) on one hand and a planecomprising areas of contact in the plate interspace between two adjacentheat exchanging plates (1, 2) that are closest to the transition part(8) in the core of plates on the other hand circumscribing a pluralityof connecting points (10) between the two adjacent heat exchangingplates (1, 2) and the inlet device (6) for the first fluid and theoutlet device (6) for the second fluid are connected to a first endplate (5) and the inlet device (6) for the second fluid and the outletdevice (6) for the first fluid are connected to a second end plate (5),each one of the first and second end plates (5) showing a surface areawhich is less than half of the surface area of one of the heatexchanging plates (1-4) in the core of plates.
 2. A plate heat exchangeraccording to claim 1 in which the intersectional line between theimaginary elongation, starting from a line of contact between theenvelope surface and the end plate (5) in a direction which is at rightangles with the plates (1-5), of the envelope surface of the transitionpart (8) on one hand and the plane comprising surfaces of contact in theplate interspace between the heat exchanging plates (1, 2) that areclosest to the transition part (8) in the core of plates on the otherhand circumscribes a plurality of connecting points (10) between the twoadjacent heat exchanging plates (1,2).
 3. A plate heat exchangeraccording to claim 1 in which the intersectional line circumscribes2-200 connecting points (10).
 4. A plate heat exchanger according toclaim 3 in which the intersectional line circumscribes 3-100 connectingpoints (10).
 5. A plate heat exchanger according to claim 4 in which theintersectional line circumscribes 5-50 connecting points (10).
 6. Aplate heat exchanger according to claim 1 in which the intersectionalline circumscribes connecting points (10) which are present mainlyevenly distributed over the existing plate areas around the inletchannel or the outlet channel in an undivided circular sector with acentral angle of at least 90 degrees, where the center of the circlecoincides with the center of the inlet channel or the outlet channel. 7.A plate heat exchanger according to claim 6 in which the central angleis more than 225 degrees.
 8. A plate heat exchanger according to claim 7in which the central angle is 360 degrees.
 9. A plate heat exchangeraccording to claim 1 in which the connecting points (10) are brazingjoints.
 10. A plate heat exchanger according to claim 1 in which thetransition part (8) is executed in one piece with the associatedconnection part (7).
 11. A plate heat exchanger according to claim 1 inwhich the end plates (5) are both mounted in the same end of the core ofplates but in different ends of a top-most situated heat exchangingplate (1).
 12. A plate heat exchanger according to claim 1 in which theend plates (5) fluid tightly connect to the core of plates and in theirouter edges show edge areas (9) at an angle to the main plane ofextension of the plates (1-5) for contacting and permanent attachment tosimilar edge areas on a top-most situated heat exchanging plate (1) inthe core of plates.
 13. A plate heat exchanger according to claim 1 inwhich the connection part (7) is cylindrical and has a larger wallthickness than the associated transition part (8).
 14. A plate heatexchanger according to claim 1 in which the transition part (8) has theform of a hollow truncated cone.
 15. A plate heat exchanger according toclaim 1 in which the transition part (8) has the form of a hollowcylinder.